1. Field of the Invention
The present invention relates to a projector, a projector control method, and a projection system, and more specifically, to a projection apparatus, a projection method, and a projection system for compositely displaying projection images projected respectively from a plurality of projection apparatuses.
2. Description of the Related Art
Conventionally, in a projection apparatus that projects a display image to be displayed on a liquid crystal panel, on a screen, a drive voltage of the liquid crystal panel is inverted on a frame basis in order to increase endurance or contrast of liquid crystals. In other words, a positive frame that is positively driven to a predetermined voltage and a negative frame that is negatively driven to a predetermined voltage are alternately arranged on the frame basis to drive the liquid crystal panel by a so-called alternating current drive. However, there are cases where brightness fluctuates in each drive of a positive frame/negative frame due to a deviation in common voltage or the like, resulting in a so-called flicker in which a projection screen flickers. For example, Japanese Patent Application Laid-Open No. H05-292518 describes reducing a flicker by inverting drives of positive and negative frames on the unit basis of each color of a liquid crystal panel (where R and B have the same phase, and G is in inverse phase with respect to R and B) in a single projector.
In addition, conventionally, projection images of a plurality of projection apparatuses are projected in a superposing manner on a same screen (stack projection), or a plurality of projection apparatuses project respective images to be displayed on a part of a single screen (multi projection). Stack projection enables a brighter image to be displayed, while multi projection enables a high definition image to be displayed in a larger screen.
During such stack projection, when each of a plurality of projectors performs alternating current drive in the conventional manner, a coincidental synchronization caused by flickers of the respective projection apparatuses sometimes results in an increase in a flicker of the display image.
It is an aspect of the invention to provide a projection apparatus, a projection method, and a projection system that solves such problems.
Specifically, the present invention provides a projection apparatus, a projection method, and a projection system capable of obtaining a projection image with a low flicker in stack projection, which superposes projection images of a plurality of projectors to form a projection image, by cancelling out flickers included in the respective images.